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crypto/x509: hardcode RSA PSS parameters rather than generating them

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Rather than generating the three possible RSA PSS parameters each time
they are needed just hardcode them and pick the required one based on
the hash function.

Fixes #41407

Change-Id: Id43bdaf40b3ca82c4c04c6588e3b643f63107657
Reviewed-on: https://go-review.googlesource.com/c/go/+/258037
Run-TryBot: Roland Shoemaker <roland@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Roland Shoemaker <roland@golang.org>
Reviewed-by: Filippo Valsorda <filippo@golang.org>
This commit is contained in:
Roland Shoemaker 2020-09-28 08:59:13 -07:00 committed by Roland Shoemaker
parent a424f6e45e
commit f33263d11a
2 changed files with 66 additions and 46 deletions
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60
src/crypto/x509/x509.go
View File

@ -351,6 +351,19 @@ var signatureAlgorithmDetails = []struct {
{PureEd25519, "Ed25519", oidSignatureEd25519, Ed25519, crypto.Hash(0) /* no pre-hashing */},
}
// hashToPSSParameters contains the DER encoded RSA PSS parameters for the
// SHA256, SHA384, and SHA512 hashes as defined in RFC 3447, Appendix A.2.3.
// The parameters contain the following values:
// * hashAlgorithm contains the associated hash identifier with NULL parameters
// * maskGenAlgorithm always contains the default mgf1SHA1 identifier
// * saltLength contains the length of the associated hash
// * trailerField always contains the default trailerFieldBC value
var hashToPSSParameters = map[crypto.Hash]asn1.RawValue{
crypto.SHA256: asn1.RawValue{FullBytes: []byte{48, 52, 160, 15, 48, 13, 6, 9, 96, 134, 72, 1, 101, 3, 4, 2, 1, 5, 0, 161, 28, 48, 26, 6, 9, 42, 134, 72, 134, 247, 13, 1, 1, 8, 48, 13, 6, 9, 96, 134, 72, 1, 101, 3, 4, 2, 1, 5, 0, 162, 3, 2, 1, 32}},
crypto.SHA384: asn1.RawValue{FullBytes: []byte{48, 52, 160, 15, 48, 13, 6, 9, 96, 134, 72, 1, 101, 3, 4, 2, 2, 5, 0, 161, 28, 48, 26, 6, 9, 42, 134, 72, 134, 247, 13, 1, 1, 8, 48, 13, 6, 9, 96, 134, 72, 1, 101, 3, 4, 2, 2, 5, 0, 162, 3, 2, 1, 48}},
crypto.SHA512: asn1.RawValue{FullBytes: []byte{48, 52, 160, 15, 48, 13, 6, 9, 96, 134, 72, 1, 101, 3, 4, 2, 3, 5, 0, 161, 28, 48, 26, 6, 9, 42, 134, 72, 134, 247, 13, 1, 1, 8, 48, 13, 6, 9, 96, 134, 72, 1, 101, 3, 4, 2, 3, 5, 0, 162, 3, 2, 1, 64}},
}
// pssParameters reflects the parameters in an AlgorithmIdentifier that
// specifies RSA PSS. See RFC 3447, Appendix A.2.3.
type pssParameters struct {
@ -363,51 +376,6 @@ type pssParameters struct {
TrailerField int `asn1:"optional,explicit,tag:3,default:1"`
}
// rsaPSSParameters returns an asn1.RawValue suitable for use as the Parameters
// in an AlgorithmIdentifier that specifies RSA PSS.
func rsaPSSParameters(hashFunc crypto.Hash) asn1.RawValue {
var hashOID asn1.ObjectIdentifier
switch hashFunc {
case crypto.SHA256:
hashOID = oidSHA256
case crypto.SHA384:
hashOID = oidSHA384
case crypto.SHA512:
hashOID = oidSHA512
}
params := pssParameters{
Hash: pkix.AlgorithmIdentifier{
Algorithm: hashOID,
Parameters: asn1.NullRawValue,
},
MGF: pkix.AlgorithmIdentifier{
Algorithm: oidMGF1,
},
SaltLength: hashFunc.Size(),
TrailerField: 1,
}
mgf1Params := pkix.AlgorithmIdentifier{
Algorithm: hashOID,
Parameters: asn1.NullRawValue,
}
var err error
params.MGF.Parameters.FullBytes, err = asn1.Marshal(mgf1Params)
if err != nil {
panic(err)
}
serialized, err := asn1.Marshal(params)
if err != nil {
panic(err)
}
return asn1.RawValue{FullBytes: serialized}
}
func getSignatureAlgorithmFromAI(ai pkix.AlgorithmIdentifier) SignatureAlgorithm {
if ai.Algorithm.Equal(oidSignatureEd25519) {
// RFC 8410, Section 3
@ -2015,7 +1983,7 @@ func signingParamsForPublicKey(pub interface{}, requestedSigAlgo SignatureAlgori
return
}
if requestedSigAlgo.isRSAPSS() {
sigAlgo.Parameters = rsaPSSParameters(hashFunc)
sigAlgo.Parameters = hashToPSSParameters[hashFunc]
}
found = true
break

52
src/crypto/x509/x509_test.go
View File

@ -2702,3 +2702,55 @@ func TestCreateRevocationList(t *testing.T) {
})
}
}
func TestRSAPSAParameters(t *testing.T) {
generateParams := func(hashFunc crypto.Hash) []byte {
var hashOID asn1.ObjectIdentifier
switch hashFunc {
case crypto.SHA256:
hashOID = oidSHA256
case crypto.SHA384:
hashOID = oidSHA384
case crypto.SHA512:
hashOID = oidSHA512
}
params := pssParameters{
Hash: pkix.AlgorithmIdentifier{
Algorithm: hashOID,
Parameters: asn1.NullRawValue,
},
MGF: pkix.AlgorithmIdentifier{
Algorithm: oidMGF1,
},
SaltLength: hashFunc.Size(),
TrailerField: 1,
}
mgf1Params := pkix.AlgorithmIdentifier{
Algorithm: hashOID,
Parameters: asn1.NullRawValue,
}
var err error
params.MGF.Parameters.FullBytes, err = asn1.Marshal(mgf1Params)
if err != nil {
t.Fatalf("failed to marshal MGF parameters: %s", err)
}
serialized, err := asn1.Marshal(params)
if err != nil {
t.Fatalf("failed to marshal parameters: %s", err)
}
return serialized
}
for h, params := range hashToPSSParameters {
generated := generateParams(h)
if !bytes.Equal(params.FullBytes, generated) {
t.Errorf("hardcoded parameters for %s didn't match generated parameters: got (generated) %x, wanted (hardcoded) %x", h, generated, params.FullBytes)
}
}
}